Examples of permanent magnet electrical machines and rotors therefor are disclosed in U.S. Pat. Nos. 6,452,301; 6,879,075; 6,967,420; and 7,619,342; in U.S. Patent Application Publication Nos. 2006/0255679 and 2008/0088193; in International Publication Nos. WO01/65663; WO2004/019467; WO2006/124704; WO2007/110282; WO2007/147922; and WO2011/012131; in European Patent Application Publication No. EP0955714; and in Japanese published patent application JP2006-158008A. Examples of electrical machine rotors with composite shafts are disclosed in U.S. Pat. Nos. 6,072,252 and 7,617,582. The disclosures of these and all other publications referenced herein are incorporated by reference in their entirety for all purposes.